Optical system



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AARON A. LEVIN Patented July 4, 1939 v UNITED STATES PATENT OFFICE omen. SYSTEM Application November 23, 1936, Serial No. 112,215

The present invention relates to optical systems and more particularly tolinear image forming optical systems for use in sound reproduction or the likeij One of the objects of the present invention is to provide a new and improved linear image forming optical system which is simple and inexpensive to manufacture, yet eilicient and accurate in operation. Another object is to provide such J a system having a relatively short mechanical length. A further object is to provide such a system having a high numerical aperture. A still further object is to provide such a system having only simple uncorrected lens elements.

V, These and other objects and advantages reside in certain novel features of construction, arrangement and combination of parts as will hereinafter he more fully set forth and pointed out in the appended claims.

Referring to the drawing:

Fig. i is a horizontal section of one embodiment of my invention. A

lfig. 2 is a vertical section thereof.

Fig. 3 is a horizontal section of 'a second emzr liodirnent of my invention.

Fig. 4 is a vertical section of the embodiment shown in Fig. 3.

Fig. 5 is a horizontal section of a third emlaodiment of my invention.

Fig. 6 is a vertical section of the embodiment shown in Fig. 5.

In the embodiment shown in Figs. 1 and 2, the linear light source S is imaged on the 111m il" with a reduction of 2 to 1 in the horizontal plane and a reduction of 18 to 1 in the vertical plane. The constants of the lens system are given in the following table:

Focal lengths T1=ln7 (13:03 w epics '113:15 1.3:?.5

The system shownvin Figs. 1 and 2 thus con- 45 sistspf three simple lenses, each having one plane surface. The cylindrical lens L; and thespherical lens le combine to image the source S in the horizontal plane while the cylindrical lensr L2 and the spherical lens La combine to image the source S in the vertical plane. The distance d4 is short in relation to the width of the lens La so that the numerical aperture of the system is high. l

The embodiment lshown in Figs. 3 and 4 also consists of. three simple lenses .each having one plane surface. The constants of this system are given in the following table:

l Focal lengths d11=40.9 R12=2.8 L11=20.3 T11=1.7 d13=0.7 142:5.4 5 R11: 10.5 T143=L6 L13=7.5

d1z=26.9 d1r=1.6 T12=1.6

I Focal lengths 621:@

T22=1.6 `1'.a1=19.35 T21=18 Raz-:4.0 Lez horizontal-:7.75 y R21=10.0 R23=1.9 L22 vertical==3.67 25 All three of the modifications shown have a cylindrical component adjacent the light source with its cylinder axis perpendicular to the axis of the source, a second cylindrical component with its cylindrical axis perpendicular to the axis of the rlrst component, and a symmetrical component. In each system each lens is a single element having one plane surface and in each 35 system only one image of the source S is formed.

From the foregoing it is apparent that I am able to attainthe objects of my invention and provide a simple, eflcient and inexpensive optical system for sound reproducing units vwhich has a relatively short overall length and a relatively high numerical aperture. Various modifications can, of course, be made without departing from the spirit of my invention or the scope of the appended claims.

I claim:

`1. A linear imageforming opticalI system for sound recording and reproducing units comprising a positive cylindrical lens, a second positive cylindrical lens spaced from the rst cylindri- '50 cal lens and having its axis perpendicular to the axis `of said first cylindrical lens, and a positive Spherical lens located closely adjacent the second cylindrical lens on the side opposite the rst cylindrical lens, the conjugate foci of the iirst cylindrical lens and the spherical lens and those of the second cylindrical lens and the spherical lens being substantially coincident, said lensesl being all simple lenses.

2. An illuminating system for forming a narrow line of light at an image plane for sound recording or reproducing, comprising a linear source of light, a positive cylindrical lens having its axis perpendicular to the axis of said source of light and spaced from said source of light to form an image of said source beyond said image plane, a second positive `cylindrical lens having its axis perpendicular to the rst cylindrical lens, said second cylindrical lens being positioned between the irst cylindrical lens and the image plane to form an image of said source beyond said image plane, and a positive spherical lens positioned between said second cylindrical lens and said image plane to bring the image formed by the rst 20 cylindrical lens'to a focus at said image plane.

i2. l 2,164,827 Y 3. An illuminating system for forming a narrow line oi light at an image plane for sound recording or reproducing, comprising a linear source oli light,a positive cylindrical lens having its axis perpendicular to the axis of said source of light and spaced from said source of light to form an image of said source beyond said image plane, a second positive cylindrical lens having its axis perpendicular to the ilrst cylindrical lens, said second cylindrical lens being positioned between the rst cylindrical lens and the image plane to form an image of said source beyond said image plane, and a positive spherical lens positioned between said second cylindrical lens vandsaid image plane to bring the image formed by the rst cylindrical lens to a focus at said image plane, each of said lenses consisting of ra single element.

AARON A. LEVEN. 

